When not authenticated, show "For companies" link

[kharann]

• The header looks like the following:
  

• A user who has no user is could most likely be a company that has discovered us for the first time. We should have alink to https://new.online.ntnu.no/company in the header.

• You can remove "Bidra", "Webshop" if you're not authenticated

• When the user is authenticated, show the regular links